An ebike is a motor vehicle. You can only ask for it to be considered as a normal push bike if it is conform to standard set in EN19514. A certificate is required for that and your supplier should provide it. Otherwise, your bike is considered a motorbike, you need type approval or submit your bike for single vehicle approval. You should read the stuff on
https://www.gov.uk/vehicle-approval/motorcycle-single-vehicle-approval website to understand the implications. A bbshd kit won't pass SVA.
The police don't normally have time to arrest everyone riding one but you should know the law.
Not really, because you can build your own motor.
This is not prohibited.
And that's exactly what I'm writing about, you want to do a test, you can do it. In the same way, if you are stopped by the police and the case goes to court (the policeman has no right to destroy your property because he is judging something), the court, as I wrote above, will refer the case to an expert - perhaps in this case to such a certification.
The end!
Why do you think the BBSHD will not pass certification? On what grounds?
The entire power of the motor is its controller, set at 250W it will give exactly that. Even if it can give a million watts!
And 250W is legal.
I still see that you can't distinguish between power potential and power use.
A police officer, if you disagree with his decision, has to start the whole procedure related to the investigation.
In this procedure, he must give the reason for the seizure, the evidence, the testimony of the witnesses (you) and, if it comes to the seizure of evidence, a receipt must be issued, justifying the seizure.
Afterwards, the police officer has 14 days to charge you, he has to do it officially, the papers have to be signed by his superior. Charges must be made in accordance with the evidence and not in accordance with conjecture. You have 60 days to appeal and go to court. The police can request to have the evidence examined by an expert, but they must inform you and have your consent.
If you do not agree, the police will apply to the court for an expert examination.